Really, lexan (polycarbonate) is very different from plexiglass
(acrylic) in how it reacts to stress & strain. Plexiglass will shatter
quite easily but lexan usually deforms. You can actually bend the
thinner stuff in a sheet metal brake.
Normally Lexan (polycarbonate) will bend into a pretzel long before it
shatters, but there is one way to make it brittle. Lexan is
mechanically tough, but chemically it's weak. Lots of common chemicals,
including household solvents and detergents, can change its behaviour
I used to work on big production-line machinery. One toolroom had a
mis-match between its very expensive 1/2" Lexan safety shields around
all the CNC machines and the cutting fluid they were using. Eventually
there was a mishap on one machine and a chunk of metal came loose. It
hit the screen and went straight through it, shattering the glazing
like a Hollywood saloon window. They had to change cutting fluids,
then replace every screen in the place.
Normally I'd have scrounged the scrap, but this stuff was so embrittled
that plant maintenance couldn't even unbolt the screen panels from the
frames without most of them cracking or breaking.
I'd also advise against Lexan for jig making. You don't need that level
of impact resistance and the stuff's a pain to work with.
Lexans attribute is that it does not scratch as easily as other plastics.
I use 3/8 all the time for jigs. It is used as trays and stuff for
1/4 is a little thin for a sled but I think it will work if you are
careful. Chamfer edges, holes and slots; cracks will propagate.
Actually Lexan (Polycarbonate) is much softer than acrylics like
Plexiglass. That is what gives it its impact resistancs, down side is at
does scratch much easier than Plexiglass.
Also cost about 2X Acrylic, 1/4" thk is around $10.00 sq/ft.
I usually have piles of plywood and MDF cabinet offcuts available for
jigs. I would have to purchase Lexan to use it. Wood is easier to
shape, brad nail, and glue for a quick jig. Typically, I'll buy Lexan,
UMHW, plastic laminate, metals... only when I have a specific
requirement, and only if it'll be for a many-use tool.
Look in any metal shop,, wood shop, plastics shop, etc... Most shop
jigs will be made from whatever materials they often work with, because
they have some, they work with the material often, and the correct tools
and sundries are already handy.
The bottom line is if you like to spend time and effort building pretty
jigs, Lexan would probably work fine. Aluminum is nice, as well. On
the other hand, if you make many jigs on the spot, specifically for an
operation at hand... There's nothing wrong with either approach, it's a
Ahhh yes... the acrylic/Lexan mistaken identity. A simple flame test
tells the difference. Google it, because my lawyer advises against
sayng too much *G*
Lexan is good enough for jet-fighter canopies, I'm told.
But the whole discussion is moot because all you need to do is call for
a price on Lexan.
I have built many a display case for a variety of jewelry stores, and
often used Lexan with a sheet of glass on top (scratch restance and
hammer resistance in an affordable sandwich).
In my solid surface fabrication, I make a lot of
jigs/patterns/templates, and I invariably use MDF and Baltic
Birch...OR..solid surface left-overs.
My favourite jig material is 1/2" phenolic, which can be bought with
laminate already attached.
Nothing quite like it.
Lexan is good stuff. The down side is that 1/4 inch is really flexible so
you would have to back it up with the plywood anyway. Cost is also an issue
unless you have it scrap.
Others have mentioned shattering. If you avoid sharp inside corners impact
resistance goes through the roof.
Poly carbonate is rather soft and will scratch easily. They do make a
scratch resistant grade but it is usually used for glazing.
One thing that does work great for jigs is Formica laminated
wood/MDF/particle board. The particle board is the last choice except for
cost if you can get sink cutouts cheap and or free. Good till you drop it
or get it wet.
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